The present invention relates generally to a system for forming color images, and more particularly to a tandem type color image formation system wherein a plurality of photosensitive members are designed in a single cartridge unit form for detachment/attachment purposes, thereby improving the integrity of maintenance.
Generally, toner image formation means for electro-photography comprises a photosensitive member acting as an image carrier having a photosensitive layer on its outer surface, charger means for uniformly charging the outer surface of the photosensitive member, exposure means for subjecting the outer surface of that member uniformly charged by the charger means to selective exposure to form an electrostatic latent image and developing means for imparting toner that is a developing agent to the electrostatic latent image formed by the exposure means to make a visible (toner) image.
The tandem system for forming color images known in the art are broken down into two types, one called the intermediate transfer belt type wherein a plurality of (e.g., four) such toner image formation means as mentioned above are provided with respect to an intermediate transfer belt (that is one example of the transfer belt) and toner images formed by these monochromatic toner image formation means on photosensitive members are successively transferred on the intermediate transfer belt so that the toner images of different colors (e.g., yellow, cyan, magenta and black) are superposed on the intermediate transfer belt, thereby obtaining a full-color image thereon, and another called the delivery belt type wherein a recording medium (e.g., a recording sheet) is carried and delivered onto a recording medium carrier belt (that is another example of the transfer belt) and toner images formed by a plurality of different monochromatic image formation means are successively transferred on the recording medium, so that the toner images of different colors are superposed on the recording medium, thereby obtaining a full-color image thereon.
For instance, one such conventional tandem image formation system is disclosed in JP-A 62-141574. This system is constructed of a plurality of joinable units, each comprising a plurality of developing and other processing means, so that the joined units are attachable to or detachable from the system proper. The system is economically advantageous because the units are individually designed as being attachable or detachable, so that a dead cartridge(s) alone can be replaced by new one.
JP-A 03-238467 describes an image formation system wherein a plurality of process units, each comprising developing means and an image carrier, are supported on one single support plate. All the process units are removed from the system at a time, and so the integrity of maintenance of the system is improved.
JP-A 09-160471 shows that process units except one for black are integrated together for easy replacement, so that the frequency of replacement of a process portion can be reduced, making control of consumable parts easy.
JP-A 09-304994 shows that a plurality of image carriers are integrally supported. In the examples, such image carriers inclusive of developing means are integrated together, so that the precision of positions of the image carriers in the system proper can be improved, resulting in elimination of color misalignments, improvements in the integrity of maintenance, and no risk of anything wrong upon insertion of the image cartridges.
JP-A 11-174772 shows that a support member is provided to locate both ends of each image formation member at a given position, thereby minimizing position misalignments of each image formation member.
In general image formation systems wherein toner is imparted from developing means to electrostatic latent images on image carriers to render the latent images visible, the service life of the image carriers differs largely from that of the developing means. Especially in the case of an image formation system using a mono-component developing agent, it is necessary to engage a control blade with a developing roller under high loads, thereby controlling the thickness of a developing agent thin layer on the developing roller. Then, the developing roller and control blade wear away due to friction between both, inevitably resulting in their service life becoming shorter than that of the image carriers. Thus, a problem with a conventional system wherein image carriers and developing means are replaced at the same time is that running costs increase because the service life of the system is governed by the developing means and so there is a need of replacing the image carriers even when they are still of avail. In particular, recently developed image carriers are being shifted to the xe2x80x9ccleaner-lessxe2x80x9d type wherein the service life of image carriers is increased because of the absence of any material that wears off the image carriers. There is thus an especially large difference in service life between the image carriers and developing means, leading to growing demands for replacement of only the developing means.
In the tandem type comprising a plurality of image carriers, the precision of color matching is largely depending on the position and shape of the image carriers. When the image carriers are replaced, color matching operation is needed after replacement, because it is difficult to keep the position and shape of the image carriers in perfect alignment between before and after replacement. Referring here to the aforesaid prior art wherein the image carriers are replaced along with the developing means, frequent color matching operations are needed, resulting in a problem that the efficiency of operation becomes low.
In a tandem system for the formation of images, the precision of color matching is largely dependent on the positions of the image carriers on which latent images are to be written. In the aforesaid prior art, write means are mounted on the system proper, and when the image carriers are replaced, there are displacements of latent images written on the image carriers, which give rise to color misalignments and cause image quality to deteriorate.
Furthermore in the tandem for forming images, the precision of color matching is considerably dependent on the precision of transfer positions on the image carriers. In the aforesaid prior art, when the image carriers are replaced, there are displacements of toner images transferred from the image carriers onto a transfer member (an intermediate transfer belt or recording medium), resulting in color misalignments and deterioration of image quality.
In view of such problems with the prior art as mentioned above, an object of the present invention is to provide a tandem system for the formation of color images wherein a plurality of image carriers are integrated into a single cartridge and developing means for each image carrier is designed to be detachable from or attachable to the cartridge, thereby improving the integrity of maintenance and cutting back on running costs.
Another object of the present invention is to provide a tandem system for the formation of color images wherein a plurality of image carriers and write means are integrated into a single cartridge and developing means for each image carrier is designed to be detachable from or attachable to the cartridge, thereby improving the integrity of maintenance, cutting back on running costs, and reducing color misalignments.
Yet another object of the present invention is to provide a tandem system for the formation of color images wherein a plurality of image carriers and an intermediate transfer belt are integrated into a single cartridge and developing means for each image carrier is designed to be detachable from or attachable to the cartridge, thereby improving the integrity of maintenance, cutting back on running costs, and improving the precision of transfer positions to reduce color misalignments.
A further object of the present invention is to provide a tandem system for the formation of color images wherein a plurality of image carriers and a recording medium carrier belt are integrated into a single cartridge and developing means for each image carrier is designed to be detachable from or attachable to the cartridge, thereby improving the integrity of maintenance, cutting back on running costs, and improving the precision of transfer positions to reduce color misalignments.
According to the first aspect of the present invention, the aforesaid objects are achievable by the provision of a tandem system for forming color images comprising at least two image formation stations, each comprising an image carrier, and charging means, developing means and transfer means disposed around said image carrier, wherein a color image is formed by passing a transfer medium through each station, characterized in that:
a plurality of image carrier are mounted on an image carrier cartridge detachable from or attachable to a system proper while they are mutually positioned, and
developing means is provided in such a way as to be detachable from or attachable to each image carrier mounted on said image carrier cartridge.
The color image formation system according to the first aspect of the invention is suitable for the case where a developing agent in the developing means comprises a mono-component developing agent.
Thus, a plurality of image carriers are integrally mounted on the image carrier cartridge while they are mutually positioned. In this case, a plurality of developing cartridges, each forming developing means for each of the plurality of image carriers, may be disposed with respect to the image carrier cartridge in a separately detachable/attachable manner. Alternatively, a developing cartridge, wherein all developing means for the plurality of image carriers may be integrated into one piece, may be disposed with respect to the image carrier cartridge in a detachable/attachable manner. Still alternatively, two developing cartridges may be disposed with respect to the image carrier cartridge in a separately detachable/attachable manner, wherein in one of said two developing cartridges there is developing means for one specific image carrier in the plurality of image carriers, and in another of said two developing cartridges all developing means for the remaining image carriers are integrated together.
Preferably in this aspect of the invention, the driving forces for the plurality of image carriers and the developing means for each of the plurality of image carriers are received at one site on the system proper and the driving force for the plurality of image carriers is divided in the image carrier cartridge and then transmitted to the developing means.
In this case, the mutual transmission of driving force between the plurality of image carriers takes place via a gear train, a belt or a chain.
Alternatively, the driving force for the plurality of image carriers may be received from one driving source of the system proper and the driving force for developing means for each of the plurality of image carriers may be received from another driving source of the system proper.
Preferably, the color image formation system according to the first aspect of the invention comprises a mechanism for adjusting color misalignments by regulating the position of at least one image carrier in the image carrier cartridge relative to other image carriers therein.
It is acceptable that around each image carrier in the image carrier cartridge there is no cleaning means for collecting the remnants of the developing agent in an independent manner.
According to the second aspect of the present invention, there is provided a tandem system for forming color images comprising at least two image formation stations, each comprising an image carrier, and charging means, write means, developing means and transfer means disposed around said image carrier, wherein a color image is formed by passing a transfer medium through each station, characterized in that:
a plurality of image carriers are mounted on an image carrier cartridge detachable from or attachable to a system proper while they are mutually positioned,
developing means is provided in such a way as to be detachable from or attachable to each image carrier mounted on said image carrier cartridge, and
write means is located and mounted at a position corresponding to each of said plurality of image carriers in said image carrier cartridge.
The color image formation system according to the second aspect of the invention is suitable for the case where the developing agent in the developing means comprises a mono-component developing agent.
Thus, a plurality of image carriers are integrally mounted on the image carrier cartridge while they are mutually positioned. In this case, a plurality of developing cartridges, each forming developing means for each of the plurality of image carriers, may be disposed with respect to the image carrier cartridge in a separately detachable/attachable manner. Alternatively, a developing cartridge, wherein all developing means for the plurality of image carriers are integrated into one piece, may be disposed with respect to the image carrier cartridge in a detachable/attachable manner. Yet alternatively, two developing cartridges may be disposed with respect to the image carrier cartridge in a separately detachable/attachable manner, wherein in one of the two developing cartridges there is developing means for one specific image carrier in the plurality of image carriers, and in another of the two developing cartridges all developing means for the remaining image carriers are integrated together.
Preferably in the second aspect of the invention, the driving forces for the plurality of image carriers and the developing means for each of the plurality of image carriers are received at one site on the system proper and the driving force for the plurality of image carrier is divided in the image carrier cartridge and then transmitted to the developing means.
In that case, the mutual transmission of driving force between the plurality of image carriers takes place via a gear train, a belt or a chain.
In accordance with the second aspect of the invention, it is acceptable that the driving force for the plurality of image carriers is received from one driving source of the system proper and the driving force for developing means for each of the plurality of image carriers is received from another driving source of the system proper.
Preferably, the color image formation system according to the second aspect of the invention comprises a mechanism for adjusting the position of at least one image carrier in the image carrier cartridge relative to other image carriers therein, thereby adjusting color misalignments.
It is preferable that the write means is constructed as a line head for performing line writing on each of the image carriers.
It is also acceptable that around each image carrier in the image carrier cartridge there is no cleaning means for collecting the remnants of the developing agent in an independent manner.
According to the third aspect of the present invention, there is provided a tandem system for forming color images comprising at least two image formation stations, each comprising an image carrier, and charging means, developing means and transfer means disposed around said image carrier, wherein a color image is formed by passing a transfer medium through each station, characterized in that:
a plurality of image carriers are mounted on an image carrier cartridge detachable from or attachable to a system proper while they are mutually positioned, and an intermediate transfer belt is provided contiguously to said plurality of image carriers, and
developing means is provided in such a way as to be detachable from or attachable to each image carrier mounted on said image carrier cartridge.
The color image formation system according to this aspect of the invention is suitable for the case where the developing agent in the developing means comprises a mono-component developing agent.
Thus, a plurality of image carriers are integrally mounted on the image carrier cartridge while they are mutually positioned. In this case, a plurality of developing cartridges, each forming developing means for each of the plurality of image carriers, may be disposed with respect to the image carrier cartridge in a separately detachable/attachable manner. Alternatively, a developing cartridge, wherein all developing means for said plurality of image carriers are integrated into one piece, may be disposed with respect to the image carrier cartridge in a detachable/attachable manner. Yet alternatively, two developing cartridges may be disposed with respect to the image carrier cartridge in a separately detachable/attachable manner, wherein in one of the two developing cartridges there is developing means for one specific image carrier in the plurality of image carriers, and in another of the two developing cartridges all developing means for the remaining image carriers are integrated together.
Preferably in the third aspect of the invention, the driving forces for the plurality of image carriers, the developing means for each of the plurality of image carriers and the intermediate transfer belt are received at one site on the system proper and the driving force for the plurality of image carriers is divided in the image carrier cartridge and then transmitted to the developing means.
Preferably in that case, the mutual transmission of driving force between the plurality of image carriers takes place via a gear train, a belt or a chain.
It is acceptable that the driving forces for the plurality of image carriers and the intermediate transfer belt are received from one driving source of the system proper and the driving force for developing means for each of the plurality of image carriers is received from another driving source of the system proper.
Preferably in the third aspect of the invention, there is a speed difference between the peripheral speed of the plurality of image carriers and the delivery speed of the intermediate transfer belt.
Preferably in that case, the color image formation system comprises a mechanism for adjusting the transfer position at which the intermediate transfer belt comes into contact with the plurality of image carriers, thereby adjusting color misalignments.
The color image formation system according to the third aspect of the invention may also comprise a mechanism for adjusting the position of at least one image carrier in the image carrier cartridge relative to other image carriers therein, thereby adjusting color misalignments.
It is also acceptable that the write means is located and mounted at the position corresponding to each of the plurality of image carriers in the image carrier cartridge.
Preferably, the color image formation system of the third aspect comprises a mechanism for adjusting the position of at least one write means mounted on the image carrier cartridge, thereby adjusting color misalignments.
It is also preferable that the write means is constructed as a line head for performing line writing on each of the image carriers.
It is also acceptable that around each image carrier in said image carrier cartridge there is no cleaning means for collecting the remnants of the developing agent in an independent manner.
According to the fourth aspect of the present invention, there is provided a tandem system for forming color images comprising at least two image formation stations, each comprising an image carrier, and charging means, developing means and transfer means disposed around said image carrier, wherein a color image is formed by passing a transfer medium through each station, characterized in that:
a plurality of image carriers are mounted on an image carrier cartridge detachable from or attachable to a system proper while they are mutually positioned, and a recording medium carrier belt is provided contiguously to said plurality of image carriers, and
developing means is provided in such a way as to be detachable from or attachable to each image carrier mounted on said image carrier cartridge.
The color image formation system according to the fourth aspect of the invention is suitable for the case where the developing agent in said developing means comprises a mono-component developing agent.
Thus, a plurality of image carriers are integrally mounted on the image carrier cartridge while they are mutually positioned. In this case, a plurality of developing cartridges, each forming developing means for each of the plurality of image carriers, may be disposed with respect to the image carrier cartridge in a separately detachable/attachable manner. Alternatively, a developing cartridge, wherein all developing means for the plurality of image carriers are integrated into one piece, may be disposed with respect to the said image carrier cartridge in a detachable/attachable manner.
Yet alternatively, two developing cartridges may be disposed with respect to said image carrier cartridge in a separately detachable/attachable manner, wherein in one of the two developing cartridges there is developing means for one specific image carrier in the plurality of image carriers, and in another of the two developing cartridges all developing means for the remaining image carriers are integrated together.
Preferably in the third aspect of the invention, the driving forces for the plurality of image carriers, the developing means for each of said plurality of image carriers and the recording medium carrier belt are received at one site on the system proper and the driving force for the plurality of image carriers is divided in the image carrier cartridge and then transmitted to the developing means.
Preferably in that case, the mutual transmission of driving force between the plurality of image carriers takes place via a gear train, a belt or a chain.
It is acceptable that the driving forces for the plurality of image carriers and the recording medium carrier belt are received from one driving source of the system proper and the driving force for developing means for each of the plurality of image carriers is received from another driving source of the system proper.
Preferably in the fourth aspect of the invention, there is a speed difference between the peripheral speed of the plurality of image carriers and the delivery speed of the recording medium carrier belt.
Preferably in that case, there is provided a mechanism for adjusting the transfer position at which the recording medium carrier belt comes into contact with the plurality of image carriers, thereby adjusting color misalignments.
Preferably, there is also provided a mechanism for adjusting the position of at least one image carrier in the image carrier cartridge relative to other image carriers therein, thereby adjusting color misalignments.
It is acceptable that the write means is located and mounted at a position corresponding to each of the plurality of image carriers in the image carrier cartridge.
Preferably in that case, there is provided a mechanism for adjusting the position of at least one write means mounted on the image carrier cartridge, thereby adjusting color misalignments.
It is also preferable that the write means is constructed as a line head for performing line writing on each of the image carriers.
It is also acceptable that around each image carrier in the image carrier cartridge there is no cleaning means for collecting the remnants of the developing agent in an independent manner.
As described above, the first aspect of the present invention provides a system for forming color images, wherein a plurality of image carriers are mounted on an image carrier cartridge detachable from or attachable to a system proper while they are mutually positioned, and developing means is provided in such a way as to be detachable from or attachable to each image carrier mounted on said image carrier cartridge. Thus, the precision of relative positions of the image carriers is so improved that any misalignments ascribable to position and parallelism misalignments of the image carriers can be prevented. Since a plurality of image carriers can be replaced at the same time, the integrity of maintenance of the system can be improved. The developing means and the image carrier cartridge can be independently replaced so that running cost reductions are achievable because even when used-up developing means are replaced, there is no need of replacing the image carriers. For replacement of used-up developing means, their replacement alone is needed and so there is no need of color matching depending on the positions and shape of the image carriers. Thus, the system for forming color images according to this aspect can have high efficiency of operation. For replacement of the developing means, only the withdrawal of the image carrier cartridge from the system proper is needed, followed by detachment of used-up developing means and attachment of new one. Thus, the operation for replacement of the developing means is so facilitated that the integrity of maintenance of the system can be improved.
The second aspect of the present invention provides a system for forming color images, wherein a plurality of image carriers are mounted on an image carrier cartridge detachable from or attachable to a system proper while they are mutually positioned, developing means is provided in such a way as to be detachable from or attachable to each image carrier mounted on said image carrier cartridge, and write means are located and mounted at positions of said image carrier cartridge corresponding to a plurality of image carriers. Thus, the precision of relative positions of the image carriers and write means is so improved that any misalignments ascribable to position and parallelism misalignments of the image carriers and write means can be prevented. Since a plurality of image carriers can be replaced at the same time, the integrity of maintenance of the system can be improved. The developing means and the image carrier cartridge can be independently replaced so that running cost reductions are achievable because even when used-up developing means are replaced, there is no need of replacing the image carriers. For replacement of used-up developing means, their replacement alone is needed and so there is no need of color matching depending on the positions and shape of the image carriers. Thus, the system for forming color images according to this aspect can have high efficiency of operation. For replacement of the developing means, only the withdrawal of the image carrier cartridge from the system proper is needed, followed by detachment of used-up developing means and attachment of new one. Thus, the operation for replacement of the developing means is so facilitated that the integrity of maintenance of the system can be improved.
The third aspect of the present invention provides a system for forming color images, wherein a plurality of image carriers are mounted on an image carrier cartridge detachable from or attachable to a system proper, an intermediate transfer belt is mounted contiguously to said plurality of image carriers, and developing means is provided in such a way as to be detachable from or attachable to each image carrier mounted on said image carrier cartridge. Thus, the precision of relative positions of the image carriers, and the precision of transfer positions is so improved that any misalignments ascribable to position and parallelism misalignments of the image carriers and transfer position misalignments can be prevented. Since a plurality of image carriers can be replaced at the same time, the integrity of maintenance of the system can be improved. The developing means and the image carrier cartridge can be independently replaced so that running cost reductions are achievable because even when used-up developing means are replaced, there is no need of replacing the image carriers. For replacement of used-up developing means, their replacement alone is needed and so there is no need of color matching depending on the positions and shape of the image carriers. Thus, the system for forming color images according to this aspect can have high efficiency of operation. For replacement of the developing means, only the withdrawal of the image carrier cartridge from the system proper is needed, followed by detachment of used-up developing means and attachment of new one. Thus, the operation for replacement of the developing means is so facilitated that the integrity of maintenance of the system can be improved.
The fourth aspect of the present invention provides a system for forming color images, wherein a plurality of image carriers are mounted on an image carrier cartridge detachable from or attachable to a system proper while they are mutually positioned, and developing means is provided in such a way as to be detachable from or attachable to each image carrier mounted on said image carrier cartridge. Thus, the precision of relative positions of the image carriers is so improved that any misalignments ascribable to position and parallelism misalignments of the image carriers can be prevented. Since a plurality of image carriers can be replaced at the same time, the integrity of maintenance of the system can be improved. The developing means and the image carrier cartridge can be independently replaced so that running cost reductions are achievable because even when used-up developing means are replaced, there is no need of replacing the image carriers. For replacement of used-up developing means, their replacement alone is needed and so there is no need of color matching depending on the positions and shape of the image carriers. Thus, the system for forming color images according to this aspect can have high efficiency of operation. For replacement of the developing means, only the withdrawal of the image carrier cartridge from the system proper is needed, followed by detachment of used-up developing means and attachment of new one. Thus, the operation for replacement of the developing means is so facilitated that the integrity of maintenance of the system can be improved.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent form the specification.
The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims]